1. Field of the Invention
This disclosure is directed to a quantum dot ink composition for inkjet printing and an electronic device fabricated using the same. More specifically, the quantum dot ink composition uses a highly viscous polymeric additive by which quantum dots can be ejected by inkjet printing and the concentration of the quantum dots can be freely controlled.
2. Description of the Related Art
Quantum dots are nanometer-sized semiconductor materials that exhibit quantum confinement effects. Quantum dots absorb light from an excitation source to reach an excited state of energy and radiate energy corresponding to the energy band gap. Therefore, the size control of quantum dots greatly affects the electrical and optical properties of the quantum dots. Based on these characteristics, quantum dots are currently applied to a variety of devices, including light-receiving devices and light-emitting devices.
The formation of thin films using dispersions of quantum dots in organic solvents is mainly achieved by coating techniques such as spin coating. However, coating techniques are not suitable for the formation of thin films over a large area and have limitations in practical use. Inkjet printing enables the formation of thin films on a large scale at low cost and is thus very attractive from the viewpoint of industrial application.
In recent years, a number of electroluminescent devices have been developed using quantum dots as materials for light-emitting layers. A typical electroluminescent device utilizes the phenomenon of light emission from a material when an electric field is applied to the material. Electrons and holes are injected into a light-emitting layer of the electroluminescent device and recombine together to form excitons, which emit light.
Spin coating is predominantly used to form light-emitting layers using quantum dots. Spin coating is, however, is not suitable for the formation of large-area light-emitting layers, which poses problems in mass production. Under the circumstances, inkjet printing is, needed to facilitate the formation of light-emitting layers over a large area. An excessively low viscosity of a composition for the formation of a light-emitting layer of a light-emitting device by inkjet printing leads to non-uniformity of the light-emitting layer. Therefore, there is a need for a high-viscosity composition that can be used to form a uniform light-emitting layer of a light-emitting device.